Among the most painful and debilitating mental health disorders, borderline personality disorder (BPD), is a major public health concern. Interpersonal problems are influential in bringing about the high distress and societal cost associated with BPD. The dangerous behaviors associated with BPD, such as suicidality, self- harm, aggression, and substance abuse, are frequently sparked by rejection or other difficult events in close relationships. Understanding the causes of interpersonal disturbance within the disorder is, thus, important for developing treatments that can help ameliorate the misery defined by BPD. This proposal outlines a project focused on emotion recognition within romantic relationships and its impact on interpersonal functioning. A large number of research studies document abnormalities in emotion recognition among individuals with BPD, but the findings are inconsistent. A majority of studies detail poorer emotion recognition among individuals with BPD. At the same time, a sizeable minority of studies detail enhanced emotion recognition amongst individuals with the disorder. The proposed study is an attempt to resolve these discrepancies, while determining the importance of physiological indices and attachment to emotion recognition and the importance of emotion recognition difficulties to interpersonal functioning. Whereas previous studies of emotion recognition in BPD have focused on empathy for strangers under cognitively cool conditions, the proposed task evaluates emotion recognition for romantic partners after being asked to write about experiences of abandonment or rejection in a close relationship. The aims of this project are as follows: 1) determine the relationship between BPD symptoms and emotion recognition difficulties, 2) examine the role of attachment style and vagal tone as mediators of the relationship between BPD symptoms and emotion recognition, and 3) determine the relationship between emotion recognition and interpersonal difficulties. The task used will be a basic emotion recognition task in which participants are asked to report the emotion pictured. Adding photographs of romantic partners will enhance the task. Participants will be sampled from the following groups: patients with BPD, patients with another personality disorder (OPD) and patients with no personality disorder (no-PD). Expected results are that emotion recognition for strangers will not differ as a function of high and low BPD symptoms, while emotion recognition for romantic partners will be enhanced by fewer BPD symptoms. Another hypothesis is that the relationship between BPD symptoms and emotion recognition will be mediated by attachment anxiety and respiratory sinus arrhythmia (RSA). A final hypothesis is that poor emotion recognition will predict disturbance in interpersonal functioning. The use of romantic partners for emotion recognition in BPD, and examining potential mechanisms of disturbed emotion recognition represent novel innovations and needed steps in research on a disorder largely characterized by difficult social relationships. This knowledge can be used to develop prevention and treatment efforts that target these specific processes.